Block for printing



June 7, 1932.

E. F. TRETVBAR, JR BLOCK FOR PRINTING Filed Aug. 1, 1931 fiwenionli'dzdardETreZbarJi;

Patented June 7, 1932 UNITED STATES EDWARD r. TRETBAR, JR, or CAMDEN, NEW JERSEY BLOCK FOR PRINTING Application filed August 1, 1931. Serial No 554,528.

My invention is a laminated block so constructed that it may be routered and kerfed, so as to provide a design or pattern of pins or ribs in desired outline rendering it suitable for printing with viscous fluids, without causing unequal strains or stresses in the block such as conmionly result in warping, which renders the block unsuitable for printm T31ocks embodying my invention are particularly adapted for the printing of linoleum, oil cloth and the like.

In accordance with my invention, the base ply of the block is preferably composed of 15, closely joined wide strips of soft wood, such as poplar, having its grain extending in what may be considered the length of the block.

To this base ply of soft wood there is applied a relatively thin ply to balance the face ply and composed of hard wood, such as maple, and made up of comparatively wide closely united strips and with the grain of such strips running transversely to the grain of the base ply. A core, preferably consist- :a' in of closely united strips of chestnut, is laid on the maple ply. The strips forming the core are relatively narrow, preferably, as compared with the strips of base ply and balancing ply and of a height substantially equal to the height of the base ply and the balancing ply together. The top or face ply, which is to be cut and kerfed to form the printing surface, is preferably composed of hard wood, such as maple, having its grain 35 disposed transversely to the grain of the core strips and being formed of the best available grade of material. This top layer or face ply is of such height or thickness that when kerfed to the desired depth to secure the intended printing effect, there remains below the kerfed portion and adjacent to the core a lamination having substantially the thickness of the lamination interposed between the core and the base.

It will be understood that the laminations are all united by a suitable adhesive under heavy pressure so as to form a composite block before routering or kerfing, and as a result of the arrangement and proportioning of the laminations the strains occurring in the block after kerfing are equalized and neutralize one another so that warping is minimizedor prevented. J

The accompanying drawingillustrates a block made in accordancewith my invention.

In the drawing, Fig. 1 is a fragmentary perspective view of a block embodying my improvements; Fig. 2 is an enlarged fragmentary perspective View of the same with parts broken away, and Fig. 3 isa fragmentary perspective View of a block after it-has been cut and kerfed.

As illustratedin the drawing, my improved block has a base ply A composed of strips 1,

2, 3, etc. of soft wood, such as poplar, the" strips preferably having greater width than thickness and the grain of the wood running in what may be considered lengthwise of the block, which is frequently six feet or more in length. The strips ofthe base ply are firmly united edge to edge. l

To the top of the base ply A is secured,v by suitable adhesive, a ply B of hard wood, such as maple, and having characteristics and coefficients of expansion and contraction and absorption the same as, or similar to, the, Wood from which the printing, face of the block is to be made. The ply B may also be built up from strips 4, 5, 6, etc; of greater Width than thickness, firmly secured edge to edge, and having the grain of the wood extending transversely to the grain of the base A core C, which provides a large part of the strength and rigidity of the block, is placed upon the ply B and consists of strips of strong wood, such as chestnut, these strips having a height which is preferably greater than of their width, these core strips being secured together edge to edge and the grain of the wood extending longitudinally of the block or in the same direction as the grain of the wood in the base ply A.

The top or face ply D of the block is made from wide strips selected from the best available stock of hard wood, such as maple, and having characteristics and expansion, contraction and absorption coefiicients the same as or similar to that of the ply B. The ply D is preferably of less thickness than the core C, but of suificient thickness that when the face of the ply D has been cut and kerfed to the desired depth, usually about one quarter inch, as shown in Fig. 3, there will remain an uncut layer (5 having substantially the "proportions, characteristics, coeificients and absorption of the ply B.

By my improved construction there is secured economically a block which is of proper 1 strength and thickness and in which the warping tendencies of the several plies neutralize one another.

Having described my invention, I claim:

1. A laminated printing block comprising a core having fixed to the opposite faces thereof plies of such relative thicknesses and characteristics that When the thicker of such plies is cut and kerfed for printing there will remain an uncut layer having substantially the proportions, characteristics, coefiicients of expansion and absorption of the other of said plies. V

2. A laminated printing block comprising a core having fixed to the opposite faces thereof plies of such relative thicknesses and characteristics that when the thicker of such plies is out and kerfed for printin there Wlll remain an uncut layer having su stantially the proportions, characteristics, coefficients so of expansion and absorption of the other of said plies and a base ply fixed to said last named ply and composed of softer Wood thansaid last named ply.

3. A laminated printing block composed of four plies of wood, the grain of each ply being transverse to the grain of the adjacent ply, the base ply of said block being of softer wood than the other plies, and the third ply from the base having a greater thickness than 40 the other plies.

4. A laminated wood printing block having a face ply, a core ply comprising strips With the grain thereof disposed transversely to the grain of the face ply, a balancing ply having the grain thereofextending in the same direction as the grain of the face ply, and a base ply, said core being of no less thickness than the base ply and balancing ply together.

5 5. A laminated wood printing block comprising four plies with the grain of the adj acent plies disposed transversely to one an other and including a core composed of narrow strips having a height at least of their width.

In testimony whereof I have hereunto set my hand this 17th day of July, 1931.

=EDWVARD F. TRETBAR, JR. 

